Theoretical investigation of the structural, electronic, magnetic and spectral properties of CumXn (X = Se, Te; m + n = 5) clusters

Based on the density functional theory (DFT), the geometric structures, relative stability as well as electronic, magnetic and spectral properties of CumXn (X = Se, Te; m + n = 5) clusters are systematically investigated with Gaussian 09. The ground state structures of CumXn clusters are found to be largely similar for X = Se and Te with minor differences. Characterized by energy gap, the stability of the CumXn clusters increases with increasing the number of Cu-X bonds and reaches the maximum for Cu2Se3 or Cu3Te2 (with the ratio m/n closest to unity). The electronic properties of CumXn clusters are related to the geometrical structures and the value of m. Particularly, Cu3Te2 cluster is found to exhibit superalkali nature with very low vertical electron affinity of 0.94 eV. The magnitudes of local magnetic moments are more than 99.99% and less than 0.01% for X and Cu atoms, respectively. The equivalent Cu or X atoms with respect to the symmetrical axis of the CumXn clusters demonstrate the same local magnetic moments due to the symmetry of the electron angular momentum related to the symmetrical axis. The IR and Raman spectra of CumXn clusters exhibit similarity for X = Se and Te. The intense UV absorption peaks at 200-250 nm for Cu4X and Cu3×2 clusters may reveal that they can act as potential UV absorption materials.